A198189 Primes from the decimal expansion of the golden ratio, phi, sorted first by the final digit index and then by length.

61, 3, 3, 1618033, 7, 887, 9887, 39887, 339887, 1618033988749, 89, 8874989, 398874989, 803398874989, 61803398874989, 2, 5, 3, 83, 683, 458683, 3, 43, 5, 3, 563, 6563, 36563, 868343656381, 180339887498948482045868343656381, 11, 811, 58683436563811

Offset

1,1

Links

Table of n, a(n) for n=1..33.

Example

For the first two digits, none of 1, 6, and 16 are prime.
The next digit, 1 is not prime, but 61 is, so a(1) = 61. 161 is not prime, so it is not included.

Prog

(PARI) v=[1, 6, 1, 8, 0, 3, 3, 9, 8, 8, 7, 4, 9, 8, 9, 4, 8, 4, 8, 2, 0, 4, 5, 8, 6, 8, 3, 4, 3, 6, 5, 6, 3, 8, 1, 1]
for(n=1, #v, x=0; p=1; forstep(k=n, 1, -1, x+=p*v[k]; p*=10; if(v[k]&&isprime(x), print1(x", "))))

Crossrefs

Cf. A186205.

Sequence in context: A132096 A051322 A345224 * A102600 A316918 A077331

Adjacent sequences: A198186 A198187 A198188 * A198190 A198191 A198192

Keyword

nonn,base

Author

Franklin T. Adams-Watters, Oct 21 2011

Status

approved